The government enacted a law on Nov. 22 to address the risks posed by tsunami in the event of a major earthquake occurring in the Pacific Ocean off the coasts of central and western parts of the country.
The special measures law outlines actions to be taken should a major quake occur along the Nankai Trough, an undersea trench in the Pacific that stretches from the Izu Peninsula, southwest of Tokyo, past Shikoku to Kyushu.
The area is thought to have experienced major quakes about once every 100 to 150 years, with a quake of magnitude 9 — the same as the Great East Japan Earthquake of 2011 — believed to strike about once every 1,000 years.
The new law could help potentially affected communities relocate to higher ground, possibly the safest measure that can be taken, but the difficulties involved include how to reach a consensus among residents on relocation and resolve land ownership issues in securing new sites.
The coastal town of Kuroshio, Kochi Prefecture, faces the risk of being swamped by waves of up to 34 meters high, the largest tsunami a coastal region in Japan would experience in a Nankai Trough earthquake, according to a study by the Cabinet Office.
The Ideguchi district located on the southern end of the town facing the Pacific is home to about 180 households totaling 400 people, and a large area of the district is likely to be flooded by tsunami in the event of such a catastrophe, experts believe.
A study group involving local government officials was launched in late October to explore the possibility of relocating the community.
“Moving to a safe place is a viable option for the benefit of future generations as well,” said Shigemasa Kaneko, a prefectural assembly member who has a house in the district. He hopes the town will determine a future course of action by holding monthly meetings and calculating the costs of such a move.
Japan has another system for supporting the relocation of houses to higher ground — a program that allows the central government to allocate funds to cover removal expenses of homes that have been hit or have a likelihood of being hit by natural disasters.
The Special Measures Law added schools and welfare facilities to the eligible relocation subsidy list.
A Kochi prefectural official said: “We welcome the Special Measures Law, which has become easier to use. If there are districts wishing to relocate, we’d be keen on offering advice.”
No community has so far relocated using the central government’s support.
In areas hit by the Great East Japan Earthquake in March 2011, efforts have been made to promote relocations to higher ground as part of reconstruction measures, but problems have hampered the process.
A total of 332 districts are eligible for community relocation measures in Iwate, Miyagi and Fukushima, the three prefectures hardest hit by the quake and tsunami.
In about 40 percent of the potential relocation sites, initial work such as land clearing has not even started, due largely to difficulties associated with land acquisition.
In some cases, the authorities have not been able to locate landowners, while other sites turned out to have multiple owners, making negotiations for buying land difficult.
The Sangenjyayanishi district in Iwanuma, Miyagi Prefecture, began relocating residences in March.
This, however, is one of the rare cases where a site had already been cleared before the earthquake, thanks to a local rezoning program, a city official said.
Since relocation does not proceed promptly, some people have indicated they intend to settle in the areas they have taken refuge in since the disaster.
“It’s possible that even if new sites are prepared for housing construction, disaster victims may not want to settle there,” an official at the central government’s Reconstruction Agency said. “We want to listen to the wishes of those affected by the disaster before proceeding with any project.”
The Uchiuraomosu district of Numazu, Shizuoka Prefecture, also faces the risk of being hit by tsunami in the event of a Nankai Trough mega-temblor.
At a meeting of residents in March 2012, 80 percent voted in favor of community relocation — an indication of the increasing sense of concern following the March 2011 disasters in the Tohoku region.
But a year later, in a survey last April, the majority of residents expressed reluctance about relocating. Any costs for new homes in the relocation area will have to be borne by the residents themselves, and this aspect clearly influenced their views, especially the elderly and those who live alone.
In contrast younger people, including those who are raising children, were still eager to relocate, and residents are expected to continue exploring the possibility of doing so.
“As more time has passed since the (March 2011) disaster, the sense of crisis has faded. This may have influenced (the recent survey result),” said Satoshi Hara, who heads a local community organization.
Suguru Mori, a professor of urban planning at Hokkaido University Graduate School of Engineering, said: “To maintain the strength of the community, it’s desirable for many people to relocate together. I hope concerned residents will hold thorough discussions with an eye to the future of their community.”
Marine data transmitter
The Japan Aerospace Exploration Agency (JAXA) and four other entities have announced they started an experiment last week to transmit data on tsunami generated far out at sea to land immediately via satellite.
A tsunami recorder with GPS was put into place 35 km off Cape Muroto in Kochi Prefecture to measure the location and height of tsunami. The recorder will transmit the data to shore-based facilities.
The research group will examine whether the data are accurate.
Until now, it has not been possible to set up a recorder more than 20 km offshore because of the need to exchange data with a base station on land via radio.
The parties involved in the test hope the new system will allow the observation of tsunami occurring more than 100 km from land, and enable early warnings and evacuations when they happen.
The four entities beside JAXA are the University of Tokyo’s Earthquake Research Institute, Hitachi Zosen Corp., the National Institute of Information and Communications Technology, and Kochi National College of Technology.
At the time of the March 2011 earthquake and tsunami, which hit parts of the Tohoku region, a recorder set up by the land ministry off the city of Kamaishi in Iwate Prefecture observed the first wave, but communications were lost due to a power outage on land.
Teruyuki Kato, professor at the University of Tokyo institute, told a news conference in Osaka that the new system will make it possible to detect tsunami generated far out at sea and issue warnings immediately. He added that he hopes the whole of the Western Pacific will be covered by the system in the future.